Has anyone checked out the quick Start rules for the new BattleTech RPG that's out soon? It has some concepts similar to MGT (attributes above a certian level give a bonus to related skill rolls, for example)
As for converting ships to Traveller, the detailed stats and construction rules BattleTech has inherently give you a lot of material to start with. TechManual has the current construciton rules for 'Mechs, Combat Vehicles, support Vehicles, Battlearmour, fighters, Shuttles, and DropShips, while Strategic Operations has the rules for JumpShips, WarShips and Space Stations.